The present invention relates to a developing device included in a copier, facsimile apparatus, printer or similar image forming apparatus and, more particularly, to a developer replenishing device for replenishing the developing device with a developer, and a developer container for use therewith.
There has been extensively used a copier, facsimile apparatus, printer or similar electrophotographic image forming apparatus which electrostatically forms a latent image on a photoconductive element, develops the latent image with charged color particles, i.e., developer, and then transfers the developed image to a paper. It is a common practice with this type of apparatus to supplement a fresh developer when a developer stored in a vessel is consumed. A device for replenishing the developer may be implemented with a hollow cylindrical container storing the developer, as taught in, for example, Japanese Patent Laid-Open Publication (Kokai) Nos. 59-188678 and 60-146265. The container is substantially entirely open at one end thereof to form a developer outlet and is rotated about the longitudinal axis thereof to sequentially discharge the developer, or powder, to the vessel of the image forming apparatus via the outlet. To replace the container with a new container filled with a fresh developer, a holder positioned horizontally on the body of the image forming apparatus is rotated downward to a vertical position about one end thereof. In this condition, the empty container is removed from the holder, and then a new container is mounted to the holder. Subsequently, the holder is again rotated to the horizontal position where the new container can replenish the apparatus with the developer. Before the new container is put on the holder maintained in the vertical position, the container is positioned such that the opening, or developer outlet, thereof faces upward, and then a cap closing the opening is removed. The container without the cap is mounted to the holder with the opening facing upward, so that the powder filling the container may not fall.
However, the prerequisite with the conventional scheme described above is that the length of the holder should not be greater than the height of the apparatus since the holder has to be rotated between the horizontal position and the vertical position about one end thereof. Generally, the apparatus is provided with as small a height as possible to meet the demand for a miniature configuration, requiring the holder and, therefore, the container to be as short as possible. As a result, the quantity of developer available with a single container is reduced, resulting in the frequent replacement of the container. In any case, the conventional replenishing device cannot be reduced in size and suffers from design limitations in relation to the internal arrangement of an image forming apparatus.
In the light of the above, we conducted a series of studies and experiments in order to implement an arrangement for allowing a person to replace the cylindrical container while maintaining the holder in the horizontal position. However, since the container is substantially fully open at one end thereof, the developer stored therein falls via the outlet of the container when the container is mounted to the holder. We, therefore, have proposed in Japanese Patent Laid-Open Publication No. 3-2881 a developer replenishing device using a container which is closed at both ends thereof and formed with a developer outlet in the circumferential wall thereof adjacent one of the closed ends. This kind of container is placed on a holder with the outlet facing upward. However, considering the fact that an image forming apparatus is used by ordinary clerks, it is likely that the container is inadvertently mounted to the holder with the outlet facing downward. Then, the developer will fall from the container and smear the apparatus and floor. In addition, a dead space is produced between the outlet and the adjoining end of the container, requiring the container to be provided with an additional length matching the dead space.